Dynamo-electric machine.



E. M. TORMIN. DYNAMO ELECTRIC MACHINE.

APPLICATION IILED JUNE 17, 1910.

1,010,533. Patented Dec.5,191 1.

UNITED STATES PATENT OFFICE.

EGMONT MAX TORMIN, 0F BROOKLINE, MASSACHUSETTS, ASSIGNOR TOHOLTZER-CABOT ELECTRIC COMPANY, A CORPORATION OF MASSACHUSETTS.

DYNAMO-ELECTRIC MACHINE.

Application filed June 17, 1910.

To all whom it may concern.

Be it known that I, EGMONT MAX TORMIN, a citizen of the United States,residing in Brookline, in the county of Norfolk and State ofMassachusetts, have invented an Improvement in Dynamo-Electric Machines,of which the following description, in connect-ion with the accompanyingdrawings, is a specification, like letters on the drawings representinglike parts.

The present invention relates to a dynamoelectric machine, and isembodied in a generator of alternating currents for signaling purposesin which regular alternating currents differing in frequency are used tooperate signaling bells on a single line, such, for example, as atelephone party line.

It is the purpose of the invention to combine in a single machine, anumber of windings adapted to be excited by a common rotating fieldmember, so that alternating currents will be delivered from the machinehaving, respectively, 1, 2, 3 and 4 cycles per revolution. It has beenthe custom, heretofore, to utilize separate generators for thedifferentcurrents, which not only largely increases the cost ofinstallation, but also requires the use of much additional power.

In accordance with the present invention, the windings for the differentkinds of current delivered are all mounted on a common core, and excitedby a single rotating field member common to all, the said field mem berconsisting of a bi-polar bar magnet having two windings so that theopposite ends thereof are oppositely polarized. The stationary member isof the usual laminated type consisting of annular laminae havinginternally projecting teeth to receive the windings, the said armaturesurrounding the rotary field member.

The invention resides mainly in novel features of construction andarrangement whereby the various currents having the characteristicsabove described can be de livered from the machine.

Figure 1 is a side elevation, partly in section, of a machine embodyingthe invention; and Fig. 2 is a general diagram of the circuits and theirconnections.

Referring to Fig. 1, the general construction of the machine issubstantially the same as that of any electric generator, the machinebeing shown as provided with a sta- Specification of Letters Patent.

Patented Dec. 5, 1911.

Serial No. 567,433.

tionary laminated armature A inclosed in a casing B, and surrounding arotating field member C which is shown as a bi-polar member mounted on arotatable shaft D and having two exciting coils E. The shaft D is shownas mounted in standards F at opposite ends, and carries the commutatorsG and G the brush holders H, H being also mounted on the standards.

The above illustration and description are mainly for the purpose ofgiving a general idea of the compactness of the machine, the features ofnovelty residing mainly in the arrangement of the windings, and in thecircuit connections which are clearly shown in the diagram, Fig. 2.

Each of the commutators G and G is provided with three insulatedcollecting portions indicated by the reference letters 9, g and g at oneend, and 9 g g at the opposite end. The coils on the field member C arewound in series and connected respectively with the collector rings 9and 9 which in turn are connected by brushes 6 and b and conductors band 6 with a battery or other source of d ect current 5 The stationarymember which surrounds the rotating field magnet is provided, inaccordance with the invention, with a plurality of windings each adaptedto produce alternating currents of different frequency. The circuitsleading from the several windings are shown as leading to a terminalboard 0, which is conventionally shown; and the electro-motive forcesinduced in the several windings can be selectively connected through theterminal board, to any line leading to the point which is to besignaled, that is to say, such, for example, as any telephone partyline, by utilizing switches commonly in use in telephone centralofiices.

The bi-polar winding (Z consists of two coils, this winding generatingan induced electro-motive force having one alternation per revolution,and the ends of this winding are connected directly through theconductors d and d with the terminal board. The winding 6 for thesix-pole generator also has the polar extremities of adjacent coils ofthe same polarity, so that an induced electro-motive force having threealternations will be produced at each revolution, and the terminals ofthis winding 6 are connected directly through conductors c and c withthe board at e. In winding the coils for the four and eight polegenerators, however, while it is possible to carry out the inding sothat the adjacent ends of the several coils will be of like polarity,the induced electro-motive forces will be neutralized if such a windingis employed, because the north and south poles of each coil will beopposite similar poles, so that as the polar extremities of the fieldmember pass, an electro-motive force in one direction will be induced inone coil, while an electromotive force in the other direction will beinduced in the coil influenced by the other pole of the field. In order,therefore, to create an induced electro-motive force of the characterrequired for the signal, I divide the windings into two sets in order tobring unlike poles opposite to each other, throughout. This results,however, in inducing two adjacent half waves in the same direction ineach half revolution, and to correct this I employ a commutator which isarranged to shift the terminal connections at each half-revolution. Thecommutator G is the one employed in connection with the winding oneterminal of the said winding being connected by a conductor with a brushf which bears on the collector ring 9 and the other terminal beingconnected through a conductor f with a brush f which bears on the othercollector ring g The collector rings 9 have projecting portions eachextending into the path of the other, and extending approximately halfway around the commutator, the said portions being separated at oppositesides of the commutator by blocks of insulating material. Theseprojecting portions are engaged by brushes h and 72, which in turn areconnected through conductors with the terminal board. The brushes arelocated between the collector rings so as alternately to engage theprojecting portions and pass from one of said portions to the other ateach half revolution of the shaft, thereby reversing the line terminals.The eight-pole winding is similarly connected with the line through thecommutator at the opposite end of the shaft, the terminals of theeight-pole winding 2' being connected through conductors 2 and 2 withthe brushes 2' and i The conductors which lead to the terminal board arearranged as previously described in connection with the other commutatorand receive the induced electro-motive force through the brushes 0 andla By this construction, the generator, through the operation of therotating field, will send out four alternating currents having,respectively, 1, 2, 3 and t cycles per revolution, thus providing forfour selective signals on a telephone party line, for example, all ofwhich can be used at the same time over different lines, if necessary.

It is necessary in utilizing the single rotary field member C, abovedescribed, that the polar extremities thereof should be narrower thanthe lengths of the shortest windings, in order to produce the regularrise and fall of the induced electro-motive force as the field memberpasses into and out of the fields of the adjacent windings. Thearn1ature must, therefore, be designed with a view to producing theregular alternating current in connection with the eight-pole winding,that is, the winding having the most coils, in a machine in whichinduced electromotive forces having 1, 2 3 and 1 alternations perrevolution. are to be produced. The twopole windings (Z, the four-polewindings f and the six-pole windings 0 must be longer than the eightpole windings, as shown in the diagram, Fig. 2, in order to produce acontinuous alternating current, and with the rotary field memberdesigned as above described the induced elcctro-motive force in thecurrents of lesser alternations will remain at its maximum effect duringa. considerable period of a revolution if the ordinary winding is used.Current waves of this form are not suitable for signaling purposes, and,in order to cause the forces to approach more nearly what is known assine waves, I increase the number of coils of the longer winding fromthe ends to the middle, so as to cause the necessary continuous rise andfall of the induced electro-motive force. This feature is illustrated inthe diagram, Fig. 2, which shows the windings as having a greater numberof turns in the middle than at the ends.

hat I claim is:

1. In an alternating current dynamo electric machine, a bi-polar fieldmember; an armature; and a plurality of sets of windings on saidarmature, each set having a different number of windings to inducealternating electric motive forces differing in frequency.

2. In a dynamo-electric machine, a bipolar field member; an armature;and a plurality of sets of windings on said armature, each set having adifferent number of wind ings to induce electro-motive forces dilt'ering in frequency, the number of turns in the windings themselves for thecurrents of lower frequency being gradually increased from the endstoward the middle of each thereof.

3. In a dynamo-electric machine, a bipolar field member; an armature; aneightpole winding on said armature, the direction of the turns in saidwinding being reversed around half the armature; and a commutator toreverse the direction of the current during half a. revolution, wherebya regular alternating current having four cycles to a revolution can bedelivered from the machine.

4. In a dynamo-electric machine, a bipolar field member; an armature; aneight pole winding on said armature, the direction of the turns in saidWinding being reversed around half the armature; a commutator to reversethe direction of the current during half a revolution, whereby a regularalternating current having four cycles to a revolution can be deliveredfrom the machine; a four-pole winding on the same armature having itscoils similarly wound, and a separate commutator for said four-polewinding.

5. I11 a dynamo-electric machine, a bipolar field member; an armature;an eightpole winding on said armature, the direc tion of the turns insaid windings being reversed around half the armature; a commutator toreverse the direction of the current during half a revolution, whereby aregular alternating current having four cycles to a revolution can bedelivered from the machine; a four-pole winding on the same armaturehaving its coils similarly wound; a separate commutator for saidfourpole winding; and a two-pole winding and a sixpole wlnding also onthe same armature,

said two and six pole windings delivering current directly to the line.

6. In a dynamo-electric machine, a bipolar field member; an armature; aneightpole winding on said armature, the direction of the turns in saidwinding being reversed around half the armature; a commutator to reversethe direction of the current during half a revolution, whereby a regularalternating current having four cycles to a revolution can be deliveredfrom the machine; a four-pole winding on the same armature having itscoils similarly wound; a separate commutator for said four-pole winding;and a two-pole winding and a six-pole winding also on the same armature,said two and six pole windings delivering current directly to the line,the coils of the two, four and siX pole windings being of higherresistance at the middle than at the ends.

In testimony whereof, I have signed my name to this specification in thepresence of two subscribing witnesses.

EGMONT MAX TORMIN.

Witnesses:

ARTHUR E. HUNTER, JAs. J. MALONEY,

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

